We have an app utilizing NFC and recently migrated from enableForegroundDispatch to enableReaderMode. Since then, we have been receiving bug reports where the user intermittently has trouble scanning tags.
I was troubleshooting remotely with a customer today who was unable to scan any tags (the app was working through yesterday). Sometimes they would receive an "NFC read error. Try again" message.
When we had them install the older version of our app which uses enableForegroundDispatch, NFC scans worked as intended. Scanning using the NFC Tools app was also working during this time, as was scanning with no app open. We tried rebooting the device and also toggling NFC on / off with no luck. It was just our app.
After much debugging, what appears to have resolved it was to fully delete our app from the device and then reinstall it. The device is a Google Pixel 2 running Android 11.
I have read countless threads about enableReaderMode and am also aware of this bug affecting kiosk apps in Android 11 (but our app isn't a kiosk). I also read about how there is a bug where Android might think our app is not in the foreground.
Is there any credence to the theory that deleting our app (vs. updating the same installed package with different builds) is what resolved this, and if so then what exactly is happening that is causing this?
Edit: I just found the threads about "NFC service dead" and am guessing this is what happened.
I have read the public code for NFC service, I cannot remember it having anything that would be affected differently by update vs uninstall/install other than possibly the Manifest(PackageManager?) permission to use NFC.
I have not looked in to details about how an app update updates the Manifest permissions, but guess an update might not update the permissions if it thinks they are not changed whereas remove/install would probably delete the whole entry and re-add it thus if there was corruption in the permission list a remove/install would likely fix it.
Also if the NFC Service is dead then other App's would not scan as well. I do seem to remember there is something in there to restart the NFC service if it had died.